1. Field of the Invention
The present invention is related an epoxy resin composition prepared by re-epoxidizing a polyfunctional aliphatic and/or cycloaliphatic epoxy resin precursor derived from an oligomer fraction of an epoxy resin of an aliphatic and/or cycloaliphatic hydroxyl-containing material. The present invention is additionally related to thermosettable compositions made from re-epoxidized polyfunctional aliphatic and/or cycloaliphatic epoxy resins and to thermosets made from said thermosettable compositions.
2. Description of Background and Related Art
Epoxidation of aliphatic and cycloaliphatic alcohols is an area of long standing interest, for example as described in EP 0 121 260, incorporated herein by reference. Disclosed in EP 0 121 260 are examples of phase transfer catalyzed epoxidation of aliphatic diols using quaternary ammonium halide catalysts with epichlorohydrin, including cyclohexanedimethanol.
WO 2009/142901, incorporated herein by reference, describes an epoxy resin composition prepared from a mixture of cis-, trans-1,3- and 1,4-cyclohexanedimethanols using several epoxidation processes. WO 2009/142901 also discloses examples of preparing various distilled grades of the monoglycidyl ethers and diglycidyl ethers of cis-, trans-1,3- and 1,4-cyclohexanedimethanols, including a high purity (>99 weight percent [wt %]) diglycidyl ether of cis-, trans-1,3- and 1,4-cyclohexanedimethanols.
When using the prior art chemistry and processes to manufacture aliphatic and cycloaliphatic epoxy resins via epoxidation of aliphatic and cycloaliphatic hydroxyl-containing materials using an epihalohydrin, it is difficult, if not impossible, to drive to full conversion; and the processes produce significant quantities of oligomeric co-products (as much as 25 wt %-40 wt % of the epoxy resin composition). The components of the epoxy resin may include for example unconverted aliphatic and cycloaliphatic hydroxyl containing material reactant, monoglycidyl ether, diglycidyl ether, oligomeric co-products, and the like. While various methods, such as, for example, distillation, are operable for removing the undesirable oligomeric co-products from the desired high purity diglycidyl ether of cis-, trans-1,3- and 1,4-cyclohexanedimethanols, no satisfactory solution exists for handling the resulting separated and isolated oligomeric co-products. The solution to date has been to use the as produced mixture of the aliphatic and cycloaliphatic epoxy resins and the oligomeric co-products together as a reactive diluent for other epoxy resins where the oligomeric co-products are simply carried into the total diluent and epoxy resin composition. Problems with this approach include preparing an epoxy resin composition having a higher than desirable viscosity induced by the presence of the oligomeric co-products; and having a reduced reactivity with curing agents.
In view of the problems with the prior art processes, it would be highly desirable to be able to fractionate an aliphatic or cycloaliphatic epoxy resin into monoglycidyl ether, diglycidyl ether, and the like, such that any residual oligomeric co-products fraction can be advantageously utilized in subsequent processes to provide novel thermosettable compositions and thermosets based on the residual oligomeric co-products fraction. Such a process and thermosettable compositions and thermosets therefrom are described in co-pending U.S. Patent Application Ser. No. 61/388,059, entitled “THERMOSETTABLE COMPOSITIONS AND THERMOSETS THEREFROM,” filed of even date herewith by Robert Hefner, Jr., incorporated herein by reference.
While the thermosettable compositions and thermosets based on the residual oligomeric co-products fraction provide numerous benefits, there is significant room for improvement of the properties provided by said compositions. Thus, it would be highly desirable to be able to fractionate an aliphatic or cycloaliphatic epoxy resin into monoglycidyl ether, diglycidyl ether, and the like, while simultaneously providing novel epoxy resins, thermosettable compositions and thermosets thereof with improved properties based on the re-epoxidation of the residual oligomeric fraction.